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package parser
import (
"fmt"
"go/constant"
"strings"
"github.com/mvertes/parscan/vm"
)
type symKind int
const (
symValue symKind = iota // a Go value defined in the runtime
symType // a Go type
symLabel // a label indication a position in the VM code
symConst // a Go constant
symVar // a Go variable, located in the VM memory
symFunc // a Go function, located in the VM code
symPkg // a Go package
)
//go:generate stringer -type=symKind
const unsetAddr = -65535
type symbol struct {
kind symKind
index int // address of symbol in frame
pkgPath string //
typ *vm.Type //
value vm.Value //
cval constant.Value //
local bool // if true address is relative to local frame, otherwise global
used bool //
}
func symtype(s *symbol) *vm.Type {
if s.typ != nil {
return s.typ
}
return vm.TypeOf(s.value)
}
// AddSym add a new named value at memory position i in the parser symbol table.
func (p *Parser) AddSym(i int, name string, v vm.Value) {
p.addSym(i, name, v, symValue, nil, false)
}
func (p *Parser) addSym(i int, name string, v vm.Value, k symKind, t *vm.Type, local bool) {
name = strings.TrimPrefix(name, "/")
p.symbols[name] = &symbol{kind: k, index: i, local: local, value: v, typ: t}
}
// getSym searches for an existing symbol starting from the deepest scope.
func (p *Parser) getSym(name, scope string) (sym *symbol, sc string, ok bool) {
for {
if sym, ok = p.symbols[scope+"/"+name]; ok {
return sym, scope, ok
}
i := strings.LastIndex(scope, "/")
if i == -1 {
i = 0
}
if scope = scope[:i]; scope == "" {
break
}
}
sym, ok = p.symbols[name]
return sym, scope, ok
}
func initUniverse() map[string]*symbol {
return map[string]*symbol{
"any": {kind: symType, index: unsetAddr, typ: vm.TypeOf((*any)(nil)).Elem()},
"bool": {kind: symType, index: unsetAddr, typ: vm.TypeOf((*bool)(nil)).Elem()},
"error": {kind: symType, index: unsetAddr, typ: vm.TypeOf((*error)(nil)).Elem()},
"int": {kind: symType, index: unsetAddr, typ: vm.TypeOf((*int)(nil)).Elem()},
"string": {kind: symType, index: unsetAddr, typ: vm.TypeOf((*string)(nil)).Elem()},
"nil": {index: unsetAddr},
"iota": {kind: symConst, index: unsetAddr},
"true": {index: unsetAddr, value: vm.ValueOf(true), typ: vm.TypeOf(true)},
"false": {index: unsetAddr, value: vm.ValueOf(false), typ: vm.TypeOf(false)},
"println": {index: unsetAddr, value: vm.ValueOf(func(v ...any) { fmt.Println(v...) })},
}
}
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